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VetBooks.ir Chapter 49

Alcohols and Glycols

Szabina Stice, Mary A. Thrall and Dwayne W. Hamar

INTRODUCTION ingested by adults as a substitute for ethanol or in an
attempt to commit suicide. In children ingestion is usually
Alcohols are organic compounds containing hydroxyl
accidental. Propylene glycol toxicosis is relatively rare in
(2OH) group(s). Alcohols that have one hydroxyl group
both humans and domestic animals. Butylene glycol toxi-
are called monohydric. These include the three alcohols
cosis is also rare and was only reported in humans after
most commonly responsible for alcohol toxicosis: metha-
use as a “recreational” drug. EG toxicosis is relatively
nol, ethanol, and isopropanol. Alcohols are also classified
common, both in humans and in domestic animals (Barton
as primary, secondary, or tertiary, according to the number
and Oehme, 1981; Mueller, 1982; Rowland, 1987;
of carbon atoms bonded to the carbinol carbon atom (the
Hornfeldt and Murphy, 1998). In humans, it is ingested
carbon atom to which the hydroxyl group is bonded). As
either accidentally, as a substitute for ethanol, or to commit
such, ethanol is classified as a primary alcohol and isopro-
suicide; approximately 5000 episodes are reported in the
panol a secondary alcohol. Methanol, in which the carbinol
United States each year (Mowry et al., 2015). The vast
carbon is bonded to no other carbon, is not a primary alco-
majority of these poisonings are unintentional, and approxi-
hol per se, but shares many of the reactivity patterns of pri-
mately one-third of the cases occur in children.
mary alcohols. Alcohols with two hydroxy groups are
Most incidents of EG toxicosis in domestic animals are
called diols or glycols. Ethylene glycol (EG) is the most
also accidental, although malicious poisonings also occur.
common glycol responsible for poisonings; EG poisoning
The mortality rate in dogs is reported to range from 50% to
is significantly more common in domestic animals than is
70% (Barton and Oehme, 1981; Rowland, 1987; Connally
alcohol toxicosis. Propylene glycol and butylene glycol
et al., 1996), and it is likely even higher in cats. EG intoxi-
poisonings are rarer and they are much less toxic than EG.
cation is the second most common cause of fatal poisoning
Alcohols and glycols are initially metabolized by
in animals, according to the American Association of Poison
hepatic alcohol dehydrogenase (ADH). Toxicosis from
Control Centers (Hornfeldt and Murphy, 1998).
alcohols and glycols results in central nervous system
The first reported case of EG intoxication in a human
(CNS) depression, ranging from decreased motor function
occurred in 1930 (Anonymous, 1930), but the toxicity of
to decreased consciousness, hypothermia, hypotension,
EG was not fully realized until more than 100 people died
coma, and death from respiratory depression, and cardiovas-
after consuming an elixir of sulfanilamide containing
cular collapse. However, metabolites of the alcohols and
96% diethylene glycol (Ballentine, 1981). This incident
glycols vary greatly in their toxicity. Metabolites of EG are
hastened final enactment in 1938 of the Federal Food,
nephrotoxic and they may result in acute renal failure. In
Drug, and Cosmetic Act, the statute that today remains
primates, metabolites of methanol may cause blindness and
the basis for FDA regulation of these products. Since
permanent neurologic abnormalities. This chapter describes then, many reports of EG poisoning in humans and ani-
toxicity and treatment of alcohols and glycols in animals.
mals have been published.
BACKGROUND ALCOHOL TOXICOSES
Reports of alcohol toxicosis are relatively rare in domestic Ethanol Toxicosis
animals compared to the reported incidence in humans.
Ethanol, methanol, and isopropanol poisoning are all quite Ethanol (ethyl alcohol or grain alcohol, CH 3 CH 2 OH) is the
common in humans. Methanol and isopropanol are usually alcohol used in mouth washes, perfumes, and alcoholic
Veterinary Toxicology. DOI: http://dx.doi.org/10.1016/B978-0-12-811410-0.00049-0
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